Method of annealing copper articles



Patented Feb. 15, 1927.

STERNER ST. 1?. MEEK, F PHILADELPHIA, PENNSYLVANIA.

METHOD OF ANNEALING- GO?PEB ARTICLES.

No Drawing.

Application filed January 18, 1926. Serial No. 82,119.

(GRANTED UNDER THE ACT OF MARCH 3. 1883; 22 STAT. L. 625.)

The invention described herein may be used by the Government, or any of its officers or employees in prosecution of the Work for the Government, or by any other person in the United States, without payment to me of any royalty thereon, in accordance with the act of March 3, 1883.

This invention relates to a method of an nealing copper articles.

The methods heretofore employed in annealing copper articles consist principally in packing the articles in charcoal, surrounding them in an atmosphere of an inert gas such as carbon dioxide or hydrogen,

or submerging them in a molten salt, such.

as potassiun'i nitrate.

All of these methods possess serious disadvantages. In the first case with the use of charcoal it is practically impossible to prevent oxidation of the surface; with the use of an inert there is always the possibility of an occlusion of large quantities of gas with a consequent struet-lu'al change in the copper tending towards brittleness; by annealing in a molten salt, the surface of the metal is to a greater or less extent corroded.

My improved method consists in packing the copper articles to be annealed in powdered metallic copper or copper dust, sealing them in a suitable container and heating container and all at a desired temperature for a desired length of time. This heating may be done by immersing the sealed containcr .in a nitrate bath, by heating in an electric furnace or by any other method of applying uniform heat which can be controlled. If desired, an electric heating coil could be fastened around the container and 40 heat thus applied directly with a thermocouple fastened in the container to indicate the inside temperature.

Copper dust of a granulation of lO-mesh or liner may be used for this purpose. Preference, however, is to be given to copper of 120-mesh or finer as very fine copper Will tend to pack more closely and more thoroughly exclude the air from the surface of the articles being annealed.

The advantages o be gained by this'mcth- 0d are the following:

First, the powdered copper having a heat conductivity practically the same as the copper articles being annealed, a more uniform anneal may be expected, with consequent greater uniformity in the grain size and temper of the annealed articles.

Second, by surrounding each article with a suli'icient thickness of powdered copper any action of the air on the surface of the copper will be prevented as the oxidizing or corrosive action of the air will be taken up by the powdered copper. It has been found in practice that a one-inch coating of copper dust is suliicient to protect a copper article for live hours of annealing at llOO F.

Third, this method will successfully prevent occlusion of in the articles being annealed, as any gases which tend to be oceluded will be taken up by the powdered copper which offers a greater surface for occlusion and so is consequently more active chemically.

Fourth, there being practically no destructive action upon the copper dust, it i'nay be used a number of times in succession, which makes this a very economical method.

I claim:

1. A method of annealing copper articles which consists in packing the article to be annealed in powdered metallic copper, sealing it in a container and then heating the entire container.

2. A method of annealing copper articles which includes packing the article to be annealed 1n powdered metallic copper.

STERNER ST. P. MEEK. 

